5-Methylthioribose 1-phosphate is an intermediate in methionine biosynthesis. It is converted from 5'-Deoxy-5'-methylthioadenosine by 5'-Deoxy-5'-methylthioadenosine phosphorylase. Then it is converted to methionine (PMID 2153115). In the methionine salvage pathway 5-methylthioribose 1-phosphate isomerase (M1Pi) catalyzes the conversion of 5-methylthioribose 1-phosphate (MTR-1-P) to 5-methylthioribulose 1-phosphate (MTRu-1-P) [HMDB]